What is Prowler?

Prowler is an open-source cloud security tool for performing audits, incident response, continuous monitoring, hardening, and forensics across AWS, GCP, and Azure. It runs hundreds of automated checks against your cloud infrastructure and tells you exactly what’s misconfigured, which compliance frameworks are violated, and what to fix.

It’s widely used by security teams, DevSecOps engineers, and cloud architects to answer: “How secure is our AWS account right now?”

Quick Start

# Install Prowler
pip install prowler

# AWS audit (uses default AWS credentials)
prowler aws

# Specific service scan
prowler aws --service s3 iam ec2

# GCP scan
prowler gcp --project-id my-project-id

# Azure scan
prowler azure --sp-env-auth

# Kubernetes scan
prowler kubernetes

# Output as HTML report
prowler aws -M html -o ./reports

AWS IAM Setup

Prowler requires read-only IAM permissions:

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": [
        "securityhub:BatchImportFindings",
        "securityhub:GetFindings"
      ],
      "Resource": "*"
    },
    {
      "Effect": "Allow",
      "Action": "sts:AssumeRole",
      "Resource": "arn:aws:iam::*:role/ProwlerScanRole"
    }
  ]
}

Attach SecurityAudit and ViewOnlyAccess managed policies for comprehensive scanning.

Key Checks by Category

IAM Security

Password policy enforcement
MFA enabled for root and IAM users
Access keys rotated within 90 days
Root account not used recently
Unused IAM credentials (>90 days)
IAM policies with admin permissions
Cross-account trust relationships

S3 Security

Public buckets (read and write)
Encryption at rest enabled
Access logging enabled
Versioning enabled for sensitive buckets
MFA delete for critical buckets
Bucket policy allows unauthenticated access

EC2 and Network Security

Security groups with 0.0.0.0/0 for sensitive ports
EBS volumes not encrypted
Default VPCs in use
Unused security groups
Instances with public IP and overly permissive SGs
IMDSv1 enabled (prefer IMDSv2)

Monitoring and Logging

CloudTrail enabled across all regions
CloudTrail log file validation
VPC flow logs enabled
GuardDuty enabled
Config service enabled
CloudWatch alarms for root activity

Compliance Framework Scans

# CIS AWS Foundations Benchmark
prowler aws --compliance cis_1.5_aws

# PCI DSS 3.2.1
prowler aws --compliance pci_3.2.1_aws

# SOC 2
prowler aws --compliance soc2_aws

# NIST 800-53
prowler aws --compliance nist_800_53_revision_5_aws

# GDPR (EU-based)
prowler aws --compliance gdpr_aws

# AWS Well-Architected Framework
prowler aws --compliance aws_well_architected_framework_security_pillar_aws

Multi-Account AWS Scanning

For AWS Organizations with multiple accounts:

# Assume role in each account
prowler aws \
  --role arn:aws:iam::123456789:role/ProwlerRole \
  --role arn:aws:iam::987654321:role/ProwlerRole

# Scan all accounts in an Organization
prowler aws \
  --organizations-role arn:aws:iam::MGMT_ACCOUNT:role/ProwlerOrgRole

CI/CD Integration

GitHub Actions (Weekly Audit)

name: Security Audit
on:
  schedule:
    - cron: '0 8 * * 1'  # Every Monday 8AM
  workflow_dispatch:

jobs:
  prowler:
    runs-on: ubuntu-latest
    permissions:
      id-token: write
      contents: read

    steps:
      - uses: actions/checkout@v4

      - name: Configure AWS Credentials
        uses: aws-actions/configure-aws-credentials@v4
        with:
          role-to-assume: arn:aws:iam::123456789:role/ProwlerRole
          aws-region: us-east-1

      - name: Run Prowler
        run: |
          pip install prowler
          prowler aws \
            --compliance cis_1.5_aws \
            -M json \
            -o ./prowler-output

      - name: Upload Results
        uses: actions/upload-artifact@v4
        with:
          name: prowler-report-${{ github.run_id }}
          path: ./prowler-output/

Output Formats

# HTML Report (visual, shareable)
prowler aws -M html -o ./reports

# JSON (for SIEM integration)
prowler aws -M json -o ./reports

# CSV (for spreadsheet analysis)
prowler aws -M csv -o ./reports

# OCSF (Open Cybersecurity Schema Framework)
prowler aws -M ocsf -o ./reports

# Send to AWS Security Hub
prowler aws --security-hub

Filtering Results

# Scan only specific services
prowler aws --service s3 iam cloudtrail guardduty

# Exclude specific checks
prowler aws --excluded-checks prowler_aws_access_analyzer_enabled

# Only high and critical severity
prowler aws --severity high critical

# Only failed checks
prowler aws --status FAIL

Prowler vs AWS Security Hub vs Scout Suite

Feature	Prowler	AWS Security Hub	Scout Suite
Multi-cloud	✅	AWS only	✅
Open source	✅	❌	✅
Compliance frameworks	40+	CIS, PCI	CIS, custom
Real-time monitoring	❌	✅	❌
Cost	Free	~$10K+/year	Free
CI/CD integration	✅	Via Lambda	✅

Prowler is the best free option for comprehensive multi-cloud auditing. AWS Security Hub is worth the investment for real-time continuous monitoring in production.

Prowler — AWS, GCP & Azure Cloud Security Tool

✅ Pros

⚠️ Cons